This section provides background information related to the present disclosure which is not necessarily prior art.
A tonneau cover made of a flexible material can be used to cover the box of a pickup truck or the like and to protect the contents thereof from the elements. Such a tonneau cover can be made of fabric, flexible plastic, or other sheet material. The tonneau cover can be secured to metal side rails along on the lateral sides of the cover and box with cooperating fastening strips. Because pickup trucks typically are used and stored outdoors, the fabric and the means of attachment of the fabric to the frame can be exposed to the elements which can include heavy moisture and extreme heat and cold, as well as dust, mud, rocks and other materials transported in the box.
Such exposure to the elements can create problems for the cover and supporting structure of the tonneau cover. Efforts to use releasable or selective coupling strips, such as hook and loop fasteners, for attaching the cover to the metal side rails tend to be subject to exposure to the elements and wear from repetitive use of convenient, selective attachment means under those conditions. Moreover, exposure to heat and cold can cause the tonneau cover to expand and contract, making the tonneau cover either loose or wrinkled in appearance, or making it difficult to secure the tonneau cover in the closed position. Thus, some movement between the various components of the tonneau cover system can be desired.
Tonneau cover systems employing the foregoing releasable or selective coupling strips can also suffer from a problem associated with premature engagement of the cooperating coupling elements attached to the frame and flexible cover, respectively. Premature engagement can occur in such systems as the user of the system unrolls the cover over the metal frame secured to the upper edges of the sides of a truck box or other open top container. As a result, wrinkles may appear in the flexible cover material following closure of the cover system. To remove the wrinkles, the user can be required to manually detach the strips of hook and loop-bearing material after the cover is stretched taut and then reattach them in a position that removes the wrinkles from the flexible cover. Again, some movement between the various components of the tonneau cover system can be desired.
Allowing such tonneau cover system component relative movement can result in forces that tend to push end caps off of the side rails. For example, a longitudinally sliding coupling strip can engage friction fit end cap during expansion and contraction, or tensioning of the tonneau cover, or otherwise. In contrast, attempts to positively retain the end caps with fasteners can inhibit the desired sliding movement of the coupling strip.